Potential presidential contender Hillary Clinton has formed "a mutually beneficial relationship" with the aerospace giant Boeing over the past five years, The Washington Post reported.

Clinton, who is the likely Democratic nominee in 2016, went to Moscow soon after President Barack Obama named her Secretary of State in 2009 to help Boeing land a $3.7 trillion deal with the Russian government to buy a dozen of its aircraft.

A month after the trip, Clinton announced in China that Boeing had "doubled" to $2 million its contribution to the U.S. pavilion at the World’s Fair in Shanghai, which had been having trouble finding sponsors and funding.

But the Post probe revealed that Clinton failed to mention that the State Department had ignored its own guidelines that initially prohibited "soliciting" Boeing for funds and then had agreed to accept just a $1 million gift from the aircraft manufacturer.

Boeing had been listed as a company to shun because it had often relied on the government for help in doing deals abroad and due to fears that any donation would be viewed as an attempt to gain advantages with U.S. authorities.

"The episode was an indicator of a mutually beneficial relationship between one of the world’s major corporations and a potential future president," Rosalind S. Helderman wrote in the Post.

"Clinton functioned as a powerful ally for Boeing’s business interests at home and abroad, while Boeing has invested resources in causes beneficial to Clinton’s public and political image."

Two months after Boeing signed its mega-deal with Russia, the company announced a $900,000 contribution to the William J. Clinton Foundation to help rebuild schools in earthquake-ravaged Haiti. The charity is now run by Hillary Clinton, along with her husband and daughter, the Post says.

Helderman said that "a potential side benefit" of her relationship with Boeing "has been the chance to strengthen ties to the kind of powerful allies in the business community who could assist a possible presidential bid."

The relationship surfaced again this month when Boeing’s in-house lobbyist, former Bill Clinton aide Tim Keating, co-hosted a fundraiser for Ready for Hillary, the super PAC supporting her potential presidential run.

Hillary Clinton spokesman Nick Merrill defended her actions as a sort of Boeing saleswoman in Russia, saying that the jet deal was "the job that every Secretary of State is supposed to do and what the American people expect of them — especially during difficult economic times. "

Merrill added, "She proudly and loudly advocated on behalf of American business and took every opportunity to promote U.S. commercial interests abroad."

Boeing spokesman Sean McCormack said the company's donations to the Shanghai expo pavilion and the Clinton Foundation were "carefully vetted to ensure" that they were "appropriate and compliant with law."